1. Field of the Invention
This invention relates to an information signal reproducing apparatus and, more particularly, to an apparatus in which from a recording medium having pilot signals for tracking control recorded therein with information signals, the information signals are reproduced.
2. Description of the Related Art
There has been known the technique that when recording a plurality of pilot signals of predetermined frequencies are recorded with the information signals, and also when recording, the tracking control is made based on the reproduced level of that pilot signal. For example, the 4-frequency method in the video tape recorder (VTR) for public use comes under the above-described technique.
By the way, concerning the pilot signal to be reproduced, its reproduction level, though the record level is the same, differs with different kinds of the recording medium. In the conventional reproducing apparatus, it is customary to use the automatic gain control (AGC) circuit. By this AGC circuit, the above described difference of the reproduced level is compensated for.
But, if the same format is applied to a plurality of kinds of recording media of greatly different characteristics when the signal is recorded, it is impossible to compensate for the difference of the reproduction level of the pilot signal. Therefore, there has been encountered a situation that when reproducing the signal from one of these recording media, good tracking cannot be done.
For example, in the VTR employing the 4-frequency method of tracking control, a system capable of using the same format in recording the video signals and four pilot signals of different frequencies on a type of tape whose metal magnetic substance coating is applied by painting means, i.e., a metal-painted tape (hereinafter called the "MP" tape) and another type of tape whose metal magnetic substance coating is applied by evaporating means, i.e., a metal-evaporated tape (hereinafter called the "ME" tape) at the same level, causes the level of the reproduced signal in the low frequency band from the ME tape to become considerably smaller than that from the MP tape and further suffers from deterioration of the signal-to noise ratio S/N. In this case, if the signal processing circuit for the MP tape is used, there is a possibility of failure of the tracking control with the use of the pilot signals reproduced from the ME tape. This results not only from the mere cause that the reproduction level is small, but also from a cause that the action of the AGC circuit contributes to an increase of the noise component in the low frequency band.